Conventionally, various types of devices have been proposed which are used for control of a torque or rotational speed to be distributed to a drive wheel of an automobile.
For example, Patent Document 1 discloses a differential gear unit 510 as illustrated in a configuration diagram of FIG. 25. The differential gear unit 510 includes two sets of pinion gear units 520a and 520b, and sun gears as external gears 523a and 523b of the pinion gear units 520a and 520b and are connected to each other via an inner connection member 522. Outer connection members 527a and 527b are connected respectively to internal gears 526a and 526b of the pinion gear units 520a and 520b, and gears 528a and 528b meshed with a gear member 529 are formed at shaft-perpendicular end surfaces of the outer connection members 527a and 527b. When a driving force is input to the inner connection member 522, the driving force is output from the carriers 525a and 525b. It is possible to control distribution of the driving force and rotational speed by rotation or stop of the gear member 529.
Patent Document 2 discloses a spur gear differential unit as illustrated in a perspective view of FIG. 26. This spur gear differential unit includes first and second sun gears 603 and 605 and first and second pinion gears 607 and 609 which are engaged with each other. The first pinion gear 607 is engaged only with the first sun gear 603, and the second pinion gear 609 is engaged only with the second sun gear 605. The first and second sun gears 603 and 605 have the same number of teeth, and different addendum circle diameters. One of the first and second sun gears 603 and 605 is subjected to positive profile shifting, and the other is subjected to negative profile shifting.
Patent Document 3 discloses a transmission device illustrated in a configuration diagram of FIG. 27. This transmission device includes pinion gear sets 718 and 719, connected respectively to output shafts 716 and 717, and a shifting mechanism 722 between the output shafts 716 and 717. The shifting mechanism 722 can be switched between shift positions S1 and S2 so as to allow the right and left shafts to correspond to braking and driving by rotation in the same direction at the shift position S1 or to be reversely rotated at the shift position S2.